1. Field of the Invention
The present invention relates to a photosensitive transfer material, a pattern formation method, and an etching method.
2. Description of the Related Art
In organic EL display devices, liquid crystal display devices, capacitance-type input devices, and the like, a pattern-formed interlayer dielectric film is provided. In order to form the interlayer dielectric film, a method is widely used in which the number of steps necessary to obtain a required pattern shape is small and, furthermore, from the viewpoint that sufficient flatness is obtainable, a photosensitive resin composition layer transferred onto an arbitrary substrate using a photosensitive transfer material is exposed through a mask having a desired pattern, is partially hardened, and then is developed.
On the basis of the difference in the photosensitive system, photosensitive resin compositions are classified into negative photosensitive resin compositions which remain as images when irradiated with an active light ray and positive photosensitive resin compositions which remain as images when not irradiated with an active light ray. In the case of the negative resin compositions, since exposed portions are hardened, it is necessary to dispose of individual substrates in a case in which the obtained pattern shape is poor. On the other hand, in the case of the positive resin compositions, since the solubility of exposed portions is increased using a photosensitizing agent that generates an acid when irradiated with an active light ray, both exposed portions and non-exposed portions are not hardened immediately before a timing of moment of pattern exposure and, in a case in which the obtained pattern shape is poor, substrates are reusable (reworkable) through full-surface exposure or the like. Therefore, from the viewpoint of being excellent in terms of so-called peeling properties in reworking processes, the positive photosensitive resin compositions are preferred.
As examples of the transfer material in which the above-described positive photosensitive resin composition is used, transfer materials described in JP4544219B, JP4654938B, and JP2010-211109A are known.
JP4544219B describes a transfer film including a support film and a resin film formed of a positive radiation-sensitive resin composition on the support film. In this document, as the positive radiation-sensitive resin composition, a chemical amplification-type positive radiation-sensitive resin composition including a polymer having a structural unit that includes an acid-decomposable functional group which is disassociated by an acid and generates an acidic functional group and a crosslinking structure, a radiation-sensitive acid generator, and an organic solvent is described, and, as the polymer having a crosslinking structure, particularly, a polymer having a crosslinking structure derived from a monomer having an ethylenic double bond is used. The document describes that, when the positive radiation-sensitive resin composition is used as a dry film resist for plate patterning, sensitivity, resolving properties, and the like are excellent, adhesiveness to substrates is excellent, residue is not generated in opening portions after development, the occurrence of cracking of the resin film after plating can be suppressed, plates being pressed into the resin film can be suppressed, the dimensional change in patterns formed in response to a change in the exposure intensity is small, and the generation of T-top by amines present in the environment can be solved. Particularly, it is described that, according to Paragraph [0050] of JP4544219B, in a case in which a plating sculpture is formed, when a metal column is formed in a groove formed by patterning a resin film by means of plating, there is a problem in that, in a resin film having a weak strength, the groove in the resin film may deform; however, when the positive radiation-sensitive resin composition of JP4544219B is used, an ethylenic crosslinking structure can be formed in the resin film and thus a firm resin film can be formed, and a metal column having a vertical side wall can be formed. In addition, in [0058] of JP4544219B, it is described that, when 0.1 mol % to 10 mol % of a structural unit including a crosslinking structure with respect to the total of other structural units is included, an appropriate molecular weight for obtaining a favorable resolution as a resist can be obtained without causing the gelation of the transfer film, and sufficient plating resistance is developed.
In a case in which a positive radiation-sensitive resin composition including the polymer having a crosslinking structure described in JP4544219B is used as an etching resist, in order to impart etchant resistance, a thermal treatment after development is essential, which is not described in JP4544219B. Meanwhile, JP4544219B describes that the resin film in the transfer film can be used with a thickness in a range of 5 μm to 200 μm.
JP4654938B describes a method in which a resist pattern is formed using a photosensitive element formed by applying a chemical amplification-type positive photosensitive resin composition onto a support. JP4654938B describes a chemical amplification-type positive photosensitive resin composition including a thermopolymerizing compound having a bond that is cut by an acid and two or more ethylenic unsaturated bonds in the molecule, a thermopolymerization initiator that initiates a thermopolymerization reaction of the thermopolymerizing compound, and a compound that generates an acid when irradiated with an active energy ray. This document discloses a positive photosensitive resin composition in which a thermopolymerizing compound having an —O—C—O— portion is used. However, the thermopolymerizing compound described in JP4654938B is not a polymer and the document describes only polymerizing compounds (monomers). Since [0021] in JP4654938B describes that the —O—C—O— portion in the thermopolymerizing compound is cut by an acid and is thus decomposed into an —OH group and a ketone compound, and the formation of this —OH group makes the thermopolymerizing compound soluble in an alkaline aqueous solution, the —O—C—O— portion in the thermopolymerizing compound does not protect an acidic group. In addition, since a hardened film after exposure is developed using methanol in examples of JP4654938B, there is no study described in JP4654938B regarding the use of a thermopolymerizing compound having an acidic group in order to improve developing properties using an alkaline aqueous solution.
JP2010-211109A describes that, by using a manufacturing method of a resin pattern including a step of applying a positive photosensitive resin composition to a film base material and then removing a solvent, thereby producing a photosensitive dry film, a step of pressing the photosensitive dry film onto a pattern-disposed substrate, thereby forming a photosensitive layer, a step of irradiating the photosensitive layer with an active light ray through a mask, a step of developing the photosensitive layer using an alkaline aqueous solution, a step of rinsing the photosensitive layer using at least one solvent selected from the group consisting of water and acidic aqueous solutions, a step of irradiating the entire photosensitive layer with an active light ray, and a step of hardening the photosensitive layer at a temperature in a range of 100° C. to 400° C., the warping of FPC obtained after a baking step is reduced and mechanical properties are improved, whereby solvent resistance can be improved. In the chemical amplification-type positive dry film of JP2010-211109A, a polyimide resin is used as an alkali-soluble resin and a naphthoquinone diazide compound is combined with the polyimide resin as a photosensitizing agent that generates an acid when irradiated with an active light ray, but there is no description regarding an aspect in which the alkali-soluble resin has a crosslinking group or a protected group of an acid group.